PEMISAHAN BERDASAR KONTAK KESEIMBANGAN

Dr. Ir. Meika Syahbana Rusli, MSc

Suatu kelompok operasi pemisahan, yang dipergunakan di dalam pengolahan pangan, dapat disebut pemisahan secara kontak keseimbangan.

Proses pemisahan berdasarkan kontak keseimbangan mensyaratkan terjadi perubahan fasa dari komponen-komponen campuran.

Peralatan yang berdasarkan pada kontak keseimbangan antara lain adalah peralatan untuk proses absorbsi atau desorbsi gas, distilasi, ekstraksi, crystalisasi dan pengeringan.

1. Absorbsi atau desorbsi gas

Kontak antara aliran gas dan aliran bahan cair

contoh : Hidrogenasi minyak, yaitu gas hidrogen

digelembungkan menembus minyak yang kemudian

bereaksi. Hidrogen diserap oleh minyak, bereaksi

dengan ikatan tidak jenuh di dalam minyak untuk

mengeraskan lemak tersebut

Karbonasi minuman. CO2 dibawah tekanan,

dilarutkan dalam bahan cair minuman sehingga

apabila tekanan dilepaskan perlahan-lahan pada

sat tutup botol dibuka akan terbentuk busa

2. Ekstraksi

Bahan cair dipergunakan untuk melakukan pemisahan suatu

komponen dari bahan padat/cair

Contoh : Ekstraksi minyak dari bahan mentah alamiah seperti

kacang tanah, kacang kedelai dan biji-bijian

Ekstraksi bahan cair-bahan cair dipergunakan di

dalam pemurnian lemak hewan

Ekstraksi pada industri gula, yaitu ketika sukrosa yang

larut dipindahkan oleh air ekstraksi dari tebu atau bit

3. Distilasi

Suatu proses dimana salah satu bagian bahan diuapkan.

Komponen yang berbeda, berbeda pula daya penguapannya.

Contoh : Pemisahan minyak atsiri

Pemisahan bau dan aroma yang tidak dikehendaki

Pemisahan anggur dan spiritus

4. Crystalisasi

Komponen yang larut dapat dipindahkan dari larutan dengan

menyesuaikan kondisi sedemikian rupa sehingga larutan

menjadi lewat jenuh dan menyebabkan terbentuknya

kristalisasi.

Contoh : Pemurnian gula dan garam

5. Pengeringan

Pemisahan air dari bahan yang tertinggal di dalam bahan pangan.

Absorbsi atau desorbsi gas

Spray Tower

In operation, the dirty gas rises up through the multiple spray zones ( number depending on service ) where the larger dust particles drop out by gravity or by impinging on the spray droplets.  High mass and heat transfer take place as the gas passes through the spray and mixes with liquor droplets.   After passing through the spray zone the gas enters the entrainment eliminator where entrained liquor droplets are removed.

Typical Application :

Coarse particle removal and gaseous absorption in industrial and power boilers, and in chlorine, ammonia, aluminum and fertilizer plants.-General gas cooling.

This is mainly used for cooling down of gas, gas pre-absorption, and dust pre-collecting. In order to adjust your installation conditions, we

are able to propose either horizontal or vertical type.

Spray Tower

Supercritical Fluid Extraction Laboratory Scale SFE

 (100mL up to 10L Systems)

EKSTRAKSI

har is the world leader in design, development, and

manufacture of solvent-free pilot / lab-scale supercritical

fluid extraction (SFE) systems. Supercritical fluid

extraction is widely used in natural products, foods and

flavors, pharmaceuticals, nutraceuticals, polymers,

chemicals, and parts cleaning industries. SFE, utilizing

CO2 instead of solvent-based or other existing

technologies, has several advantages. The laboratory

SFE scale models from Thar starts from 100mL up to

10L. Models can include co-solvent pump, fractionation

and recycling.

SFE applications in the food and pharmaceutical

industries:

Decaffination of coffee and tea Extraction of essential oils (vegetable and fish oils) Extraction of flavors from natural resources

(nutraceuticals) Extraction of ingredients from spices and red peppers Extraction of fat from food products Fractionation of polymeric materials Extraction from natural products Photo-resist cleaning Precision part cleaning

Pilot Scale SFE (2L up to 50L Systems)

Pilot scale requirements differ greatly from application to application and from company to company. Since the pilot stage is designed to be a stepping-stone to production levels, Thar emphasizes flexibility and cost effectiveness in the design and development of its pilot scale systems. The modular design of Thar's systems enables quick and easy testing and optimization of processing parameters.

For companies who need additional support at the pilot stage, Thar offers a complete line of process and application services and toll processing. Additionally, Thar has its own multi-purpose pilot scale systems in-house that can be utilized for a wide range of experimental programs.

Process Scale SFE (75L up to 1500L Systems)

har's family of process scale systems includes both multi-purpose and application specific systems. Standardized configurations based on our 200 plus years of combined experience, process development expertise and patented and patent-pending technology range up to 1500L volume in a single vessel and 6000L in total volume. Beyond standard systems, Thar offers the option of custom configurations to best suit your application(s), including innovative packages to increase energy efficency.

This expertise has been proven across multiple continents and includes packages designed to GMP specifications. Emphasizing continuing product R&D, Thar designs and develops components and entire systems. Thar's pumps, vessels and all other components that go into complete systems are specifically optimized for carbon dioxide and designed for manufacturability to reduce manufacturing costs, providing a cost savings that get passed to you.

Steam DistillationEssential oils are used in perfumes, handmade soaps, bath salts, lotions and other natural bath and body products. These volatile oils can be used individually or blended to create a special bouquet. One of the ways essential oils are extracted from plant material is through steam distillation. The following diagram provides an overview of the steam distillation process.

Distilasi

1. Fresh or dried botanicals are placed in the retort or still.

2. Pressurized steam is introduced into a lower chamber of the  retort and passed through the botanical ingredients to vaporize the volatile oils in the plant material.

3. The steam and oil vapor mixture is then passed through a condenser.

4. The essential oil is then extracted from the floral water or hydrolat in the separator.

Distillation Expertise Distillation Applications

  - Solvent recovery systems  - Product purification  - Solvent drying

Operation Types  - Continuous, batch, vacuum, pressure

Distillation Types  - Ideal and non-ideal systems  - Binary and multi-component separations  - Special distillation techniques     - Azeotropic     - Extractive     - Reactive     - Pressure Swing

Distillation Column Types  - Sieve and valve tray  - High performance valves  - Structured packings  - Dumped packings

Materials of Construction  - SS, CS  - Nickel alloys  - Chloride resistant alloys  - AL6XN, Alloy 2205  - Glass lined steel  - Teflon lined steel  - Other exotic alloys

Other Distillation Equipment

Shell & tube heat exchangers - Full thermal design and ratings- Condensers, reboilers, interchangers, vaporizers, etc.

Specialty design heat exchangers- Falling film reboilers- Low pressure drop condensers

ReactorsVapor/liquid separatorsVacuum systemsLiquid/liquid separatorsLiquid/liquid contactors

(extraction columns)

Crystalisasi

Continuous Forced Circulation Crystallizer

Continuous Forced Circulation Crystallizer

o an "active volume", designed case by case, to get both required an "active volume", designed case by case, to get both required residence time for crystal growth and mother liquor desupersaturation.

o a given agitation (recirculation rate) rated to control the extent of supersaturation arising from the evaporation, and to keep the temperature difference in the heat exchanger within reasonable limits.

o a special design of the liquid-vapor separation area to minimize the carry over losses and avoid the formation of an excessive amount of fines, which is highly detrimental to crystal growth.

It is much like a simple forced circulation evaporator, but it includes specific features to allow correct crystallization, namely

Depending upon specific process requirements, additionaldevices can be provided. They are:

internal baffles, used mainly for excess mother liquor overflow and /or withdrawal of fines when crystal growth is slow or disturbed by impurities build-up (see Figure 2),

elutriation leg, to improve product purity and to deliver a narrow crystal size distribution ,

an internal scrubbing section to reduce to very low value the carry over losses, or even to provide stripping or absorption devices when a volatile compound must be recovered.

Typical products are:NaCl (food or technical grade), KNO3, Na2, SO4, K2 SO4 NH4Cl, Na2CO3H2O and Citric acid

Oslo Type Crystallizer Close Type

Oslo type crystallizer also called classified-suspension crystallizer is the oldest design developed for the production of large, coarse crystals.

The basic design criteria are twofold:

desupersaturation of the mother liquor by contact with the largest crystals present in the crystallization chamber

keeping most of the crystals in suspension without contact by a stirring device, thus enabling the production of large crystals of narrow size distribution

Typical products are: (NH4)2 SO4 Na2SO4 AgNO3 hydrated mono sodium glutamate mono ammonium phosphate (MAP)

The classifying crystallization chamber is the lower part of the unit. The upper part is the liquor-vapor separation area where supersaturation is developed by the removal of the solvent (water for most applications). The slightly supersaturated liquor flows down through a central pipe and the supersaturation is relieved by contact with the fluidized bed of crystals. The desupersaturation occurs progressively as the circulating mother liquor moves upwards through the classifying bed before being collected in the top part of the chamber. Then it leaves via the circulating pipe and after addition of the fresh feed, it passes through the heat exchanger where heat make-up is provided. It is then recycled to the upper part.

Oslo Type Crystallizer Open Type

is worth to be considered when very large settling areas are required or when the vessel must be fabricated out of high cost alloys or metals.